The Role of the Humic Substances in the Fractioning of Heavy Metals in Rodrigo de Freitas Lagoon, Rio de Janeiro - Brazil

One of the main results of the processes related to urbanization is the contamination of the adjacent water bodies. Inserted in this context, the Rodrigo de Freitas lagoon is situated in the south zone of the city of Rio de Janeiro. This ecosystem receives several inputs containing all sorts of pollutants, including heavy metals. The present work aimed to study the partitioning of heavy metals in the sediments of Rodrigo de Freitas and the influence of organic matter in this fractionation dynamic. The results of these analyses presented the contents of organic matter as an important metal-capturing agent. Fractionation of organic matter resulted in a predominance of humine. Heavy metal partitioning showed that the metals bound by the water-soluble phase have no significant concentrations. Special features such as, reducing sediment, high levels of organic matter and fine grain size have transformed this ecosystem in an effective deposit of pollutants, where heavy metals are not available in easily reactive fractions

Potentially mobile of heavy metals on the surface sediments in tropical hyper-saline and positive estuaries

ABSTRACT Estuarine sediments represent important pools of trace metals, released from both anthropogenic and natural sources. Fluctuations in the water column physicochemical conditions, on the other hand, may transfer metals from solid to liquid compartment and resulting in contamination of the surrounding environment. The present research was carried out to evaluate the weakly bounded heavy metal levels in tropical hyper-saline and positive estuaries, in order to quantify its potentially availability. The monitoring includes five metals (Cd, Cr, Cu, Pb, Zn) and cover nine estuaries in Rio Grande do Norte state/Brazil, including four hypersaline and five true estuaries. 50 surface sediment samples were collected in each estuary. At the same time, organic matter concentrations were evaluated in order to help explaining possible local variations in heavy metal levels. Organic matter results (0.7% - 7.3%) suggest the positive Potengi estuary as the most critical environmental quality situation. On the other hand, according to heavy metals levels, both Conchas and Potengi estuaries registered the higher concentrations of Cr. The highest concentrations were observed in the hyper-saline estuaries, with the exception of the Zn. The present study revealed that the watershed occupation has significantly influenced the heavy metal concentrations in the estuaries

The transfer and resulting negative effects of nano- and micro-plastics through the aquatic trophic web—A discreet threat to human health

The ubiquitous occurrence of plastic nano- and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment, especially in aquatic ecosystems. Hundreds of aquatic species, from different trophic levels, have been affected by this “new” contaminant, which has been reported mainly in their digestive tracts. Consequently, current knowledge about plastic nano- and micro-particle spread and the potential impact on aquatic biota is growing rapidly. However, there is a significant lack of understanding of the trophic spread of microplastic contamination and integration of knowledge derived from laboratory assays with that from field research is difficult. Field experiments are unable to deal with differentiating between directly and indirectly ingested plastic microparticles. On the other hand, laboratory assays evaluating the influence of plastic microparticles and of their adhered or constitutive toxins on representative species cannot satisfactorily simulate the real environment. As a result, little is known about the effective transfer of plastic particles through the trophic net and the resulting human health risks. The present review seeks to gather information that can give a more accurate idea of the current situation and future challenges to be faced in mitigating the environmental and human effects of plastic particle pollution in aquatic, particularly estuarine, ecosystems

Negative Impacts of Trace Metal Contamination on the Macrobenthic Communities along the Santos Port Complex—Brazil

Port sites represent one of the most impacted coastal areas; this impact is due to intensive anthropogenic pressures. In addition to the port complex itself, associated activities, such as indiscriminate disposal of pollutants, including trace metals, affect the local ecosystem. Macroinvertebrate benthic communities are one of the most effective bioindicators of environmental health because of their importance as a primary food source for many fish, birds, and mammals, as well as their influence on sediment stability and geochemical composition. This article evaluates the benthic macrofauna in the Santos Estuarine System (SES), the location of the Santos Port Complex (SPC), linking trace metal levels to differences in microbenthic community structure and pollutant bioavailability. The distribution of Cd, Ni, and Pb was directly related to organic matter deposits, while Cu and Zn appeared to result from port activities. The SES contained a poor benthic macroinvertebrate community, resulting from the contaminated muddy sediments. A significant negative correlation was found between the macrobenthic diversity and concentrations of Cu in the soluble phase; this implied the pollution-induced degradation of the macrobenthos in SES